Category Archives: plant diseases

Methods for controlling plan diseases

Dogwood in the Santa Cruz Mountains

dogwood_RoblesEarlier this year the flowering plums were the first trees to welcome the beginning of spring. Then came the flowering cherries, crabapples, pears, redbuds and lilacs. But now the flowering dogwoods take over as the stars of the show. They are blooming everywhere I go. Whole neighborhoods, lined with dogwood trees, are coming to life.? I? know of several beautiful specimens along Hwy 9 that bursts into bloom this time of year covered in snowy white, pink or rosy blossoms. There are many types of dogwoods and every garden has the perfect spot for at least one. What better way to honor Earth Day 2014 than to plant a tree?

When thinking about where to plant your dogwood tree consider what role you want cornus_florida_closeupthe tree to play in your garden. You might place it where it becomes the main focal point especially during the spring flowering season but also where you can enjoy the brilliant fall foliage. Maybe one located at the back of the garden would be nice drawing the eye along a path and the flowering shrubs growing along the edges.

Dogwoods need good drainage. If your garden has heavy clay soil plant your tree in a raised bed. They make excellent understory trees in high filtered shade if the air circulation and drainage are good. With 2-3″ of mulch dogwoods thrive in full sun, too. The fungal disease anthracnose is not usually a problem here in our summer dry area if drainage is good. Hybridizers have successfully crossed the Japanese dogwood, cornus kousa, with the eastern dogwood, cornus florida, to create the wonderful disease resistant Stellar series. Also the native Pacific dogwood, cornus nutalli, has been crossed with the eastern variety to produce Eddie’s White Wonder. Both are good choices.

cornus_florida_closeup2The beautiful flowers of the dogwood are actually bracts, a leaf-like structure surrounding a flower. The colorful bracts of poinsettias, the magenta bracts of bougainvilleas and the bracts of the dogwood are often mistaken for flower petals. No matter what you call them, the blossoms are spectacular.

Dogwoods attract a variety of wildlife. All sorts of critters use this tree for food and shelter. The giant silk moth and several species of butterflies favor dogwoods as host plants. The spring flowers provide nectar to bees and other pollinating insects. Robins and sparrow are just two of the bird species than build nests on the horizontal branches and many others seek shelter in the leaves. The high calcium, high fat, fleshy red fruits are eaten by 35 species of birds including titmice, juncos and waxwings.

The fruit of flowering dogwood is poisonous to humans but the root bark was used by Native Americans as a fever reducer, skin astringent, an anti diarrhea agent and as a pain reliever for headache and backache relief. It was also use to counteract the effects of many poisons and as a general tonic. The flowers were infused to reduce fever and relieve colic and several plant parts were used as medicine for blood diseases like malaria.

Because dogwood leaf litter decomposes more rapidly than most other species it has been planted on abandoned strip mines and used for urban forestry projects. The wood is hard, strong and shock resistant, making it suitable for wood products that need to withstand rough use like tool handles, roller skate wheels, golf club heads and knitting needles and spools.

Dogwoods look so great in our area because we get some winter chill.? Some of cornus_capitata_closeupmy favorite varieties include cornus capitata also known as Evergreen or Himalayan Dogwood. It’s a slow growing tree which will reach 20 ft tall after about 25 years and has large white blossoms.

Other common favorites with rosy flowers are Eastern dogwood, Cherokee Chief and Cherokee Brave. Their leaves turn glowing red in fall with fruit lasting well into winter. There are lots of white blooming varieties also and this tree is the parent of the exceptional hybrid Eddie’s White Wonder and the anthacnose-resistant Stellar Pink.

The Japanese dogwood, cornus kousa, starts blooming several weeks later than the Eastern varieties and continues for 5-6 wks. The flowers open along with the leaves which is different than its relatives. This dense multi-stemmed tree grows to 20 ft tall.? With raspberry-like fruits that persist into winter and leaves that turn yellow or scarlet in autumn it’s a beautiful addition to the garden.

Remember a mature leafy tree produces as much oxygen in a season as 10 people inhale in a year. Trees clean the soil and air of pollutants, act as windbreaks and can muffle noises.

Gardening Tips for August & IPM

I go out into my garden and look around daily. I pick basil for tonight's bruschetta, parsley for the potatoes and a few Sungold cherry tomatoes that don't make it into the kitchen but are eaten on the spot. I count 10 hummingbirds around my 3 feeders, the Ruby-crowned kinglets are scouring the trees for spiders and other bugs and the Wilson's warblers have found the thistle sock.

But what's this? Some of the fuchsia leaves and buds are curled, there are notches in the impatien balfourii and I see white furry things on the trunk of the crabapple.  The weather is hot one day and foggy the next. Better adjust my watering schedule, too. Whether you're seeing some of these same problems in your garden or have different issues that you don't know how to handle, here are some tips to help you decide what you can live with and what you can't.

Integrated pest management or IPM is a fancy name for common sense. By planting the right plant in the right place you can prevent most pest infestation. Pick your battles.Take action against insects only when they pose a significant threat to your plant.

Plants can usually survive with a little bug damage. Insects that are natural predators often will eventually arrive and handle your bug problem.  Picking them off by hand or spraying them off with water often works, too. Some vegetable plants may need to be protected with insect barriers or row covers. Simple traps for earwigs, slugs and snails are effective, too. Vacuuming is another method of controlling pests. Tilling the soil often disrupts the breeding cycle of insects like the rose slug. Encourage beneficial insects to visit your garden by planting a variety of plants. Use natural biological insecticides like Bt and nematodes that have minimal environmental impact.

If you feel you must spray for soft bodied insects like mites, choose insecticidal soap. This may sound strange but by not killing all the pests there will be some left in the gene pool that are not resistant to the organic or chemical sprays. Those left will dilute any resistant genes that appear.

Regular monitoring is the cornerstone of IPM. This is where that daily walk in your garden with a beverage comes in. You can see if a problem is getting out of control or not.

The fuchsia gall mite is one problem that I keep tabs on or the hummingbirds aren't happy. If your fuchsias aren't blooming and the leaf tips look curled up and deformed, your plants are infested with fuchsia gall mite.  First discovered on the West Coast in 1980 it is often mistaken for a disease because of the way it distorts and twists fuchsia leaves and flower buds.  The damage caused can be debilitating.  The leaves curl and distort so much that normal photosynthesis is disrupted and weakened plants fail to bloom  Infested plants usually recover if further mite damage is controlled.

Prune off all distorted foliage and buds.  This may be the best method of control as petroleum oil or insecticidal sprays need to be made every 4-7 days to disrupt the mite life cycle and will result in the mites becoming resistant. Neem oil is not recommended for use on fuchsia flowers.

There are several gall mite-resistant fuchsias, both hanging and upright, that are every bit as showy as the traditional fuchsia varieties.  if you have been plagued by fuchsia mites, try growing one of these instead. A list from Crescent City Fuchsia growers is available at http://www.ccfuchsia.net/ccfuchsia5.htm.

If you have a problem in your garden and don't know what to do, feel free to email me. I'm always happy to help a fellow gardener.

 

Sudden Oak Death Syndrome ( SOD )

InDay Lilypreparing for a consultation for another site under native oak trees at risk for SOD I found the latest host list published by the Sudden Oak DeathTask Force . The new list updated March 2008 also lists plants naturally infected and lots of information re. spreading the fungus as well as tips on sanitation. The latest information on prevention and keeping the immune system of your trees up if also available. I did find that a few of the plants that I was going to recommend for homeowners with oaks on their property have now been listed as vectors. They are coffeeberry, toyon, berberis aquifolium, manzanita and some varieties of ceanothus. This is important information for all of us to know.